论文标题
系外行星和棕色矮人的矿物雪花：云颗粒与{\ sc hylands}的凝结和碎片化
Mineral Snowflakes on Exoplanets and Brown Dwarfs: Coagulation and Fragmentation of Cloud Particles with {\sc HyLandS}
论文作者
论文摘要
棕色矮人和系外行星提供了独特的大气制度，可提供有关其形成路线和进化状态的信息。建模矿物云颗粒的形成是准备任务和仪器（例如crires+，jwst和ariel）的关键，以及{\ sc polstar}（例如{\ sc polstar}）可能的偏光仪。目的是支持更详细的观察结果，要求对微物理云过程有更深入的了解。我们扩展了我们的动力学云形成模型，该模型可以处理成核，凝结，蒸发和沉降的混合物质云颗粒，以始终建模云颗粒粒子碰撞。新的混合代码{\ sc hylands}应用于{\ sc draft-phoenix}（t，p） - profiles的网格。有效的培养基理论和MIE理论用于研究光学特性。湍流是碰撞的主要驾驶过程，碰撞成为云基群的主要过程（$ p> 10^{ - 4} \，{\ rm bar} $）。碰撞产生三个结果之一：零散的气氛（$ \ log_ {10}（g）= 3 $），凝结气氛（$ \ log_ {10}（g）= 5 $，$ t _ {\ rm eff} \ rm eff} \ leq 1800 （$ \ log_ {10}（g \，）= 5 $，$ t _ {\ rm eff}> 1800 \，{\ rm k} $）。光波长（HST）处的云粒子不透明斜率随着碎片的增加而增加，中红外波长处的硅酸盐特征也是如此。混合力矩键方法{\ sc hylands}证明了在确保元素保护的同时结合矩和箱方法的可行性。它提供了一种强大而快速的工具，用于捕获粒子碰撞的一般趋势，并与其他微物理过程保持一致。碰撞在系外行星和棕色矮人的气氛中很重要，但不能被认为仅受到打击。碰撞的光谱效应使观察数据的云粒度和材料组成的推断变得复杂。
Brown dwarfs and exoplanets provide unique atmospheric regimes that hold information about their formation routes and evolutionary states. Modelling mineral cloud particle formation is key to prepare for missions and instruments like CRIRES+, JWST and ARIEL as well as possible polarimetry missions like {\sc PolStar}. The aim is to support more detailed observations that demand greater understanding of microphysical cloud processes. We extend our kinetic cloud formation model that treats nucleation, condensation, evaporation and settling of mixed material cloud particles to consistently model cloud particle-particle collisions. The new hybrid code, {\sc HyLandS}, is applied to a grid of {\sc Drift-Phoenix} (T, p)-profiles. Effective medium theory and Mie theory are used to investigate the optical properties. Turbulence is the main driving process of collisions, with collisions becoming the dominant process at the cloud base ($p>10^{-4}\,{\rm bar}$). Collisions produce one of three outcomes: fragmenting atmospheres ($\log_{10}(g)=3$), coagulating atmospheres ($\log_{10}(g)=5$, $T_{\rm eff} \leq 1800\, {\rm K}$) and condensational growth dominated atmospheres ($\log_{10}(g\,)=5$, $T_{\rm eff} > 1800\, {\rm K}$). Cloud particle opacity slope at optical wavelengths (HST) is increased with fragmentation, as are the silicate features at mid-infrared wavelengths. The hybrid moment-bin method {\sc HyLandS} demonstrates the feasibility of combining a moment and a bin method whilst assuring element conservation. It provides a powerful and fast tool for capturing general trends of particle collisions, consistently with other microphysical processes. Collisions are important in exoplanet and brown dwarf atmospheres but cannot be assumed to be hit-and-stick only. The spectral effects of collisions complicates inferences of cloud particle size and material composition from observational data.
